Silicon dioxide layers are commonly thermally grown in the processing of semiconductor devices in which a silicon or silicon carbide surface is heated in a moist atmosphere to grow silicon dioxide (hereinafter frequently referred to as grown, or thermal, oxide).
This process reduces the surface thickness of an underlying substrate, which has been converted to silicon dioxide (SiO2) and this is disadvantageous in many applications, for example, in trench type Schottky devices. Thus, in such devices, parallel trenches are formed in a silicon surface and the sides and bottoms of the trenches are oxidized by a thermal process to form an insulated SiO2 coating in and lining each trench. Each trench is then filled with a conductive polysilicon. The silicon or silicon carbide, or other substrate material mesas between trenches have a critical width, and the process of growing the oxide on the trench walls will reduce the mesa widths by 2000 Å to 4000 Å, depending on the thickness of SiO2 which is needed.
Further, the growth of oxide, particularly, on silicon carbide substrates is very time consuming and it would be desirable to form a grown oxide layer on SiC more quickly. For example, it will take 6.5 hr to grow 36 nm of oxide on SiC at 1100 C.
Furthermore, oxidation of SiC produces carbon clusters and a high density of trapped charges at the oxide/SiC interface. [See K. C. Chang, J. Bentley, L. M. Porter, J. of Ele. Mat. 32, 2003, 464-469; and Y. Hijikata, H. Yaguchi, M. Yoshikawa, S. Yoshida, Appl. Surf. Sci., 184 (2001) 161-166.] Thus, another long time post-oxidation annealing is normally used after the thermal oxidation. The quality of the oxide/SiC interface by thermal oxidation process therefore constrains the application of thermal grown oxide in the MOS device.
It would also be very desirable to form an SiO2 insulation layer on a silicon parent substrate without excessive consumption of the silicon surface to create the SiO2 layer.